Certain materials, such as ceramics, glass, nickel superalloy, etc., can not be easily machined. The machining of such materials often results in tool wear in addition to poor surface precision of the work piece. For example, the machining of the ceramic material takes various forms, such as grinding, ultrasonic machining, laser machining, discharge machining, ion beam machining, etc. These various forms of the ceramics machining have their own advantages and disadvantages; nevertheless, they have one thing in common in poor removal rate of chip. If the machining of a ceramic material is done by grinding, the grinding cost takes up to 70%–80% of the total cost of the production of the ceramic element. In another words, the grinding of the ceramic material is not only time-consuming but also costly. In view of the fact that the ceramic material, the metal material, and the plastic material are widely used to make the high-tech products, and that the ceramic material has excellent physical properties in terms of heat resistance, corrosion resistance, and hardness, the ceramic material is an indispensable element in the development of the high-tech products. For this reason, it is imperative that the efficiency of the current machining technology must be enhanced.
As illustrated in FIG. 1, a laser assisted machining (LAM) of the prior art is used to machine a ceramic workpiece in such a way that the ceramic workpiece is continuously subjected to heat by laser so as to soften the ceramic workpiece. Accordingly, a machining tool is also subjected to a very high temperature when it comes in contact with the workpiece. In addition, the softened workpiece is vulnerable to tiny thermal crack, temper deterioration, and weakness in strength in the course of the machining process. In light of the large-scale nature of the laser heating process, the physical properties of the workpiece are susceptible to variation in a large-scale pattern. For example, when a CBN (boron nitride) tool is subjected to a temperature in excess of 1470 degrees in Celsius, the crystalline structure of the boron nitride changes from cubic form to hexagonal form, thereby resulting in a substantial weakness in strength of the CBN tool. In another words, the machining efficiency of the tool is enhanced under the circumstances that the temperature of the workpiece remains at 1410 degrees in Celsius. In case of the workpiece temperature at 1570° C., the strength of the tool is greatly weakened. The continuous heating process of laser tends to undermine the longevity of the machining tool.